Thursday, 2 December 2010
Friday, 15 May 2009
Testing UMTS by Dan Fox, Anritsu
Its nearly three years since I wrote an FAQ on UMTS Testing. So when I got my hands on this book the other day, I so wanted to read it. It would be a while before I manage to go through the book in detail but my initial impression is that this book looks quite good.
Since the book deals with Protocol Testing, the testing has been grouped into three categories:
- Integration Testing
- Conformance Testing
- Interoperability Testing
There is a chapter explaining each of these. The Conformance testing is of interest to me as I have been involved directly and indirectly with this for quite some years now. The book explains the process, standards required and submission of tests to GCF/PTCRB.
For those whom testing does not hold much charm, they can gain greater understanding of the concepts by reading Part II of the book. One thing I really liked in this book is that the diagrams explain the concepts very well. Rather than copying them straight from the 3GPP specifications, they have been improved and re-done by the author. Basic things like 'Dynamic TFCI selection' and 'Layer 2 transport channel processing flow for the 12.2 kbps RMC' are explained clearly using the diagrams.
There is just the right amount of detail in the chapters for Physical Layer, Layer 2 (MAC, RLC, PDCP) and Layer 3 (RRC, NAS). Further chapters show message flow sequence charts explaining things like 'setting up of speech call' and 'location updating procedure'. I have some basic sequence diagrams for message flow in the Tutorial section but the ones in the book are comparatively more detailed.
The book mainly covers UMTS, with an introduction to HSPA. It would be worthwhile to have the next edition covering LTE in detail. The main reason being that there are lots of changes in the case of LTE. The Air Interface has changed, the channels are different. The NAS messages and entities are different. UMTS (and HSPA) use TTCN-2 for testing but LTE uses TTCN-3. UMTS does not use MIMO (MIMO available for HSPA from Release 7 onwards) but LTE would generally always use MIMO.
Overall, this seems to be a useful book and I am looking forward to reading it in detail.
Monday, 25 February 2008
This one is from Arvind's blog:
TTCN-3 core language is nothing more than simple text with well-defined syntax and semantics. The syntax is defined using Backus-Naur Form. What this means is that any text editor can be used to write TTCN-3 test cases. Such test cases are quite different in dynamic behaviour from C or Pascal. Still, it is quite easy for programmers well-versed with procedural languages to get used to TTCN-3 easily. There are many similarities - keywords, data types, variables, control statements, functions, operators, operator precedence, just to name a few.
The language is structured in a way that allows high level of flexibility. Test system definition is modular. In fact, an important unit of a test suite is a module which would contain one or more test cases or the control part of a test suite. Concurrency of operation is possible because components can execute in parallel. Of course, execution is serialized at the level of hardware unless the multi-processors are involved. Parameterization is possible just as it was possible in TTCN-2. Concepts of PICS and PIXIT still apply because they are fundamental to any conformance testing.
More Information is available at:
- Arvinds Blog
- TTCN-3 in a nutshell - University of Ottawa
- Links to TTCN-3 Tutorials, etc - University of Ottawa
- TTCN-3 Core Language - ITU
- ETSI's TTCN3 Homepage
- TTCN-3 User Conference Archieves
Finally, you may be wondering why I am discussing TTCN-3 on this blog. This is because those of us who work in testing side will know very well that most of the test scripts are written in TTCN. At present TTCN-2 is used and there is only one big player for that which is Telelogic. This is because they have some patents which restricts competetion. To bypass this, ETSI pioneered TTCN-3 which is open source and anybody can create a compiler for TTCN-3.
As a result, TTCN-3 is being widely adopted for testing now. Its already being used for WiMAX, IMS and SIP testing. In future it would be used for LTE as well.